The long-term objective of this project is to develop specific, high affinity inhibitors of mammalian collagenases which might be therapeutically useful in the control of diseases which involve the destruction of connective tissue. Included in this category are rheumatoid arthritis, chronic periodontal disease, corneal ulceration, epidermolysis bullosa and the metastasis of certain tumors. These inhibitors should also be useful in defining the biochemical role of collagenases in these diseases as well as in studying the normal metabolism of collagen. In addition, they should be useful in determining the mechanism of collagenase action and in defining the differences in substrate specificity exhibited by collagenases from different sources. Specifically we propose to synthesize by solid phase and solution methods a series of model peptide substrates designed to elucidate the steric and catalytic properties of the enzyme from rabbit V2 carcinoma and from human synovial tissue. In addition, certain fragments of the collagen chains will be tested as substrates. We propose also to continue our synthesis of bifunctional peptide analogs of the collagenase-sensitive site in collagen which combine a metal binding group such as a thiol with a peptide carrier which binds to the extended active site of the enzyme. Several such inhibitors have already been synthesized and tested with amphibian collagenase. We propose to test these inhibitors with mammalian collagenase also. A novel feature of this proposal is that in some of the proposed inhibitors, the scissile peptide bond will be replaced with a non-hydrolyzable metal binding group. These compounds should combine the binding properties of the residues on both the C- and N-terminal sides of the cleaved bond, resulting in higher potency. The most effective of the inhibitors will be examined for their ability to inhibit tumor growth, tumor metastices and joint erosion in appropriate animal model systems.